This invention relates generally to a dental model base assembly and more particularly to such an assembly in which a premanufactured dental base may, at the option of a technician, be attached either to a disposable dental articulator or to a metal articulator.
Damaged teeth may be repaired or replaced by crowns, bridge inlays or other common dental prosthesis. A successful repair requires accurate alignment and visual uniformity of the repaired tooth with the patient's other teeth. Typically, a model is made of the patient's teeth and the prosthesis is fitted to the model and adjusted to achieve proper alignment and visual uniformity.
The model is typically formed by having a patient bite into a pliant casting material which cures to create a mold cavity having a negative impression of the patient's teeth and gums. The mold can be of all or any portion of the patient's gum line. A castable material is then poured into the negative impression to create a stone replica or dental model of the patient's teeth and gums.
To facilitate prosthesis development, the replica of the damaged tooth or teeth is severed from the remainder of the dental model. In one prior art system, severability is achieved by positioning the knurled end of a tapered dowel pin in the uncured stone material in correspondence with the damaged tooth or teeth. The dowel pin or pins must be carefully aligned and held in position which requires skill and time. Once the casting of the gum and teeth has hardened, the cured dental model is positioned adjacent an uncured dental model base which is held in a dental base mold. The tapered portion of the dowel pins protruding from the dental model are positioned in the uncured dental model base. To prevent bonding of the damaged tooth model with the dental model base, wax may be placed between the base and the dental model and around the tapered portion of the dowel pins associated with the damaged tooth model.
Once the dental model base has cured, a saw cut on each side of the damaged tooth model is made down to the dental model base which allows removal of the damaged tooth model and the attached dowel from the rest of the dental model.
After the damaged tooth model is removed, the prosthesis can be fitted and adjusted without the spacial limitations encountered when the damaged tooth model is joined to the full dental model. After the prosthesis is made and attached to the dental model segment, the tapered dowel attached to the dental model segment is guided into its respective aperture in the dental model base which guides the dental model segment to its position in the dental model. Alignment and visual conformity are then assessed.
Alignment is ascertained by evaluating the registration of the repaired tooth with the dental model of the patient's opposing teeth. This is achieved by connecting the upper and lower dental model to an articulator. If the prosthesis is out of alignment or does not visually conform to the rest of the patient's teeth, the dental model segment containing the damaged tooth can be removed, adjusted and returned to the dental model base. This process is repeated until proper alignment and visual conformity is achieved. Thus, the model of the damaged tooth may be removed and inserted into the base repeatedly. This repeated removal and reinsertion can damage the fit of the tapered portion of the dowel pin within the cast dental model base which decreases the accuracy of the alignment procedure.
Several plastic dental model bases exist. Examples are described in U.S. Pat. No. 5,788,489. These plastic bases facilitate mounting a cast dental model and overcome some of the difficulties inherent in cast dental model bases. However, plastic bases must also be attached to articulators.
The Vertex® articulator is one disposable articulator typically used to check the alignment of repaired teeth. The Vertex® articulator has a ball and socket joint that permits alignment of the articulator with dental model bases supporting a variety of different dental models. The Vertex® articulator socket member is formed with a tongue opposite the socket. The tongue is typically glued to a slot in the rear portion of the cast dental model bases. The Vertex® articulator may also be glued to slots formed in plastic dental model bases. An example is depicted in FIG. 9 of U.S. Pat. No. 5,788,489.
Other common articulators are metal and the dental model is attached semi-permanently by applying a bonding agent, such as plaster, to the dental model base and the articulator. An example is depicted in FIG. 15 of U.S. Pat. No. 5,788,489. While metal articulators may be separated at the hinge, protruding portions of the articulator obstruct access to the dental model from certain directions. A technician may prefer using one type of articulator in certain circumstances and the other when the circumstances are different.